The purpose of this study is to compare the methods of body composition in a heterogeneous group of adult men and women, as measured by underwater weighing, dual energy X-ray absorptiometry, skin folds, and bioelectrical impedance analysis. A total of 50 adult (over 18 yr.) male and female volunteers will be recruited for the study over a five year period (3/1/96-2/28/2001). Since the study began approximately one year ago, a total of 14 volunteers have completed the study. We expect to recruit approximately 8 additional volunteers during each of the remaining four years. No preliminary analysis of the data on the first 14 volunteers has, as yet, been completed.